document type does not allow element %1 here; missing one of %2 start-tag

Cause:

The mentioned element is not allowed to appear in the context in which you've placed it; the other mentioned elements are the only ones that are both allowed there and can contain the element mentioned. This might mean that you need a containing element, or possibly that you've forgotten to close a previous element.

Example:

textexample textexample

Bad:
textexample
textexample
Good:
textexample textexample

Solution:

textexample textexample

References: